This invention relates generally to metallic components and more particularly for a method of producing fatigue-resistant and damage-tolerant metallic components.
Various metallic components, such as gas turbine engine fan and compressor blades, are susceptible to cracking from fatigue and damage (e.g. from foreign object impacts). This damage reduces the life of the part, requiring repair or replacement.
It is known to protect metallic components from crack propagation by inducing residual compressive stresses therein. Methods of imparting this stress include shot peening, laser shock peening (LSP), pinch peening, and low plasticity burnishing (LPB). These methods are typically employed by applying a “patch” of residual compressive stresses over an area to be protected from crack propagation, for example a tip of a gas turbine engine compressor blade. While this process inhibits crack growth, it may leave the component subject to crack initiation at the boundary between the “patch” and the remainder of the component. This is an undesirable failure mode which may shorten the useful life of the component and/or increase the difficulty of repair.
Accordingly, there is a need for a method of protecting metallic components from crack propagation while promoting an acceptable failure mode thereof.